Cassini Significant Events
for 01/07/09 - 01/13/09

The most recent spacecraft telemetry was acquired on Jan. 13 from the
Deep Space Network tracking complex at Canberra, Australia.  The
Cassini spacecraft is in an excellent state of health and all
subsystems are operating normally. Information on the present
position and speed of the Cassini spacecraft may be found on the
"Present Position" page at:
http://saturn.jpl.nasa.gov/operations/present-position.cfm.


Wednesday, Jan. 7 (DOY 007):

The S47 background sequence was uplinked to the spacecraft today.
All files are registered and active on board.  S47 will begin
execution on Friday, Jan. 9.

Friday, Jan. 9 (DOY 009):

The spacecraft propulsion system fuel-side repressurization activity
was completed today as one of the final activities in S46.  The
low-pressure helium latch valve, LV-30, was opened Jan. 7.
Twenty-four hours later, the high-pressure helium latch valve, LV-10,
was cycled for 5 minutes and 7 seconds, successfully filling the
fuel-side bipropellant tank.  The next day LV-30 was closed and
Over-Pressure-1 fault monitor was disabled.  This activity optimized
the fuel-oxidizer mixture ratio and is the last planned
repressurization for the Cassini spacecraft.  A project debrief will
be held Jan. 14.

The final science observation of S46 was another in the series of
Imaging Science (ISS) pickets that repeatedly observe a particular
latitude and longitude to detect short-term temporal variation.

The S46 sequence concluded and S47 began execution today at 8:29 AM
PST.  The sequence will run for 39 days and conclude on Feb. 17.
During that time there will be a targeted encounter of Titan and
three non-targeted flybys - two of Titan and one of Rhea. Three Orbit
Trim Maneuvers are scheduled, numbered 180 through 182.

The S47 Saturn/Mimas Live Inertial Vector Propagator (IVP) Update
kickoff meeting was held today.  It is already known that this update
will be a "Go" so work has begun on generating the files.  Uplink is
planned for Tuesday, Jan. 20.

At the top of S47, ISS continued a Titan cloud monitoring campaign.
This campaign contains observations that are typically requested when
Titan is at low phase and when the Cassini spacecraft is around 1 to
2 million km away from Titan. These observations provide isolated
snapshots and are intended to improve our understanding of how often
there are clouds on Titan, where they're appearing as the seasons
change, how fast and in what direction the winds blow, and also how
the haze evolves with the season.


Monday, Jan. 12 (DOY 012):

On Saturday, Uplink Operations sent commands to the spacecraft for
the Saturn/Rhea DOY 012-014 Live IVP Update.  Registration has been
verified and the commands are ready to execute as planned.

The cover of the January 2009 edition of Discover Magazine features a
Cassini Radio Science simulated image of ring structure and particle
sizes. The measured high-resolution X-band signal extinction profile
provides the structure information assuming azimuthal symmetry.  The
measured differential effects on the X-, S-, and Ka-band signals
provide the particle size information used to color code the image.

Today the Optical Remote Sensing instruments stared first at the star
Gamma Crucis, then Alpha Crucis, as they were occulted by the rings.
Stellar occultations in the current orbit are able to penetrate the B
ring to study structures within it.

Tuesday, Jan. 13 (DOY 013):

The Spacecraft Office (SCO) hosted the S52 Engineering Activities
Review today.  At this type of review SCO verifies that all
activities have been scheduled for ongoing operations, as well as
those needed for the health and safety of the spacecraft.
Science Planning wrapped up integration of the S49 background
sequence and associated activities today.  Input files and
documentation were passed to Uplink Operations for the final sequence
development process.  The process will last approximately 10 weeks
with S49 beginning on-board execution on Mar. 26.

Visit the JPL Cassini home page for more information about the
Cassini Project: http://saturn.jpl.nasa.gov/>
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